Pressure-sensitive hectograph transfer element



April 6, 1965 D. A. NEWMAN ETAL 3,177,086

PRESSURE-SENSITIVE HECTOGRAPH TRANSFER ELEMENT Filed Dec. 15. 1961 IW////// lll W 1 E\\\\\\\\\\\\\\ E? /0 A flv fl I I INFRARED LAMPS7/////////l', 3/ ///////////fi'7,' 3 IR ABSOEBIN -I IMAGES omeauAL sHEE#4 HEAT TEANSFEERE-D IMAGES HEAT 3 1 \f e a z s l A x0 E? 4 2 ELECTEOSCDPIC POWDER {I IMAGEs INVENTORS 2 //a Douylas A Newman flgarz 7.chZaZz%aae/' United States Patent 3,177,086 PRESSURE-SENSITHVEHECTOGRAPH TRANSFER ELEMENT Douglas A. Newman, Glen Cove, and Allan T.Schlotzhauer, Locust Valley, N.Y., assignors to Columbia Ribbon andCarbon Manufacturing Co. Inc., Glen Cove, N.Y., a corporation of NewYork Filed Dec. 15, 1961, Ser. No. 159,695 3 Claims. (Cl. 117-361) Thisinvention relates to novel pressure-sensitive hectograph transferelements.

Conventional hectograph transfer sheets carry a pressure-transferablehectograph layer of wax and dyestuff or other color-forming material.When a master sheet is superposed with a hectograph transfer sheet andpressure is applied, the said hectograph layer, corresponding to thepressured areas, transfers to the master sheet. In the spirit or gelatinduplication. process, many copies can be made from the prepared mastersheet.

Conventional wax-base hectograph transfer sheets have certaindisadvantages which materially affect their performance. For instance,the transfer properties of these sheets varydepending upon thetemperature at which they are being used due to the low hardening andsoftening temperatures of the wax binder material. When cold, the binderhardens and is less frangible, less tacky and has less aflinity for themaster sheet to which it is transferred. When warm, the binder softensand transfers readily but the transferred images are not sharp butrather are broad and somewhat fuzzy.

Also, Wax-base hectograph compositions are applied to the transfer sheetfoundation as a hot melt and the temperatures used must be high enoughto melt the wax and reduce it to a smooth coatable consistency. Suchtemperatures have a detrimental eifect on many dyestuffs and tend to tarthem whereby the dye particles fuse together as non-uniform clusters.This results in transfer layers wherein the dyestuff is not uniformlydispersed.

Wax-base hectograph compositions also have the disadvantage that the waxbinder material is insoluble in the spirit duplicating-fluids so thatmuch of thedyestuff carried in image form on the master sheet isinsulated against contact with the spirit solvents by the wax binder.Only that amount of the dye which is at or near the surface of theimages can be leached out in the duplicating process. Thus a relativelylarge percentage of the image on the master sheet constitutes Waxbinding material and trapped dyestuff which remains behind on theexpired master sheet and is wasted for imaging purposes.

Another serious disadvantage of the conventional hot melt wax hectographtransfer layers is that they are, meltable at temperatures in the rangeof 140 F. and above and therefore give rise to many problems when usedin heat transfer processes such as those involving the use of infraredradiation. Attempts to use these conventional hectograph transfer sheetsin heat transfer processes have failed since the wax coatings melt atthe prevailing temperatures which generally range between 150-450 F. andflow or in some cases completely block off to the master sheet, givingrise to a blurred master sheet and inferior or unrecognizable copies.

Therefore it is an object of the present invention to prepare hectographtransfer sheets which are temperaturestable and which retain uniformfrangibility characteristics over a wide range of temperatures.

It is another object to prepare hectograph transfer sheets in the coldby means of solvents thereby avoiding the problem of tarringthedyestuffs.

It is still another object to prepare hectograph transfer sheets onwhich the transfer layer does not melt or be- 3,177,086 Patented Apr. 6,19.65

come flowable at the temperatures used in the heat-transfer processes.

It is another object of the present invention to prepare spirithectograph transfer sheets in which substantially all of the dye isavailable for producing copies, thereby allowing for the preparation ofmore numerous copies through the spirit duplicating process thanheretofore possible.

It is a further object of the present invention to prepare spirithectograph transfer sheets in which the binding material does notinterfere with the availability of the dye for the imaging of copysheets, and which is not wasted on the expired master sheet.

These and. other objects and advantages are accomplished as more fullyset out in the following description and drawing in which:

FIGURE 1 represents a diagrammatic cross-section, to an enlarged scale,of a transfer sheet according to this invention.

FIG. 2 represents a diagrammatic cross-section, to an enlarged scale, ofan imaged original sheet, master sheet and hectograph transfer sheetsuperposed and under the eflects of infrared radiation, the sheets beingseparated for purposes of illustration.

FIG. 3 represents the imaged master sheet prepared ac cording to theembodiment of FIG. 2.

FIG. 4 represents a diagrammatic cross-section, to an enlarged scale, ofa master sheet and a transfer sheet bearing on the transfer layersurface xerographicallyplaced electroscopic powder images under theeffects of heat, the sheets being spaced for purposes of illustration.

FIG. 5 represents the imaged master sheet prepared according to theembodiment of FIG. 4.

According to the present invention, hectograph transfer elements havebeen developed which have the aforementioned advantages and whichprovide for the sharper, cleaner, more reliable imaging of master sheetsthan heretofore possible.

The transfer elements of the present invention comprise a flexiblefoundation carrying a volatile-solvent-applied frangible transfer layerwhich is substantially completely transferable to a master sheet in.areas impressed with imaging pressure, said transfer layer comprisingfrom 3% to by weight of a synthetic thermoplastic filmforming bindermaterial, an amount of a miscible mixture of at least two oleaginousmodifying agents in excess of the amount of said binder material, saidmiscible mixture including from 20% to 80% by weight of at least oneoleaginous material which is substantially compatible with said bindermaterial and from 80% to 20% by weight of at least one oleaginousmaterial which is substantially non compatible with said bindermaterial, and from to by weight of a spirit-soluble hectograph dyestuff,said dyestufl being substantially insoluble in said oleaginous materialsand insoluble in the volatile solvent used to apply said transfer layer.

The thermoplastic binder preferably comprises a material which issoluble in the spirit duplicating fluids. Thus, alcoholand preferablyethanol-soluble materials such as ethyl cellulose and polyvinyl acetateare preferred. -iowever, in many instances the spirit duplicating fluidmay consist of or have added thereto any organic solvent which dissolvesthe particular resin or film-former used.

The oily mixture forms a critical part of the present composition sinceit is the oily materials which render the thermoplastic binderfrangible. It has been found that at least two different oily materialsmust be used. These r materials must be miscible with each other and atleast one of them must be compatible with. the binder material While atleast one other is substantially incompatible with the resinous binder.

The incompatible oily material, if used alone with the thermoplasticbinder, tends to be exuded or sweated from the resinous layer. This isdetrimental in that the exuded oil tends to stain master sheets storedin contact therewith. More important, however, is the eventual loss offrangibility of the transfer layer as the; amount of incompatible oiltherein gradually decreases.

The compatible oily material, if used alone with the thermoplasticbinder, may render it frangible in some cases, depending upon the degreeof compatibility, However, the compatible oil acts as a plasticizer forthe binder and gradually the .frangibility is lost as a solid plasticfilm is formed.

Where non-miscible incompatible and compatible oils such as mineral oiland castor oil are used, each oil acts independently and the transferlayer sweats the mineral oil while the castor oil plasticizes the layerand frangibility is lost. However, these two oils may be used togetherprovided that a third oil is added which is miscible with both of them.For instance, when rapeseed oil is added,

a miscible solution of the three oils is formed, the mineral andrapeseed oils being incompatible with the resinous binder material, inthe case of ethyl cellulose, while the castor oil is compatibletherewith.

It is not completely clear why the incompatible oily is material of thepresent invention is not exuded or sweated from the present transferlayers or why the compatible oily material does not gradually plasticizethe binder therein and change the frangibility of the layer. It appearsthat the incompatible oil, white it has no attraction for the bindermaterial per se, gains an attraction or bonding to the binder by meansof thecompatible oil, with which it is miscible. Likewise the compatibleoil is prevented from plasticizing the binder and forming a continuoussolid non-frangible film by the presence of the incompatible oil whichgives the layer a discontinuous or,

porous structure and prevents the formation of a continuous layer. Thecompatible oil seems to lose its plasticizing properties due to itsmixture with the incompatible oil while the incompatible oil. seems tolose its tendency to be sweated from the layer due to its mixture withthe compatible oil.

It has been found that the. miscible oily mixture must contain from atleast 20% by weight up to about 80% by weight of the compatible oil. Oilmixtures containing over 80% compatible oil and less than 20%incompatible oil exhibit a tendency to plasticize the binder and causeloss of frangibility upon extended periods of storage whereas mixturescontaining over 80% incompatible oil and less than 20% compatible oilexhibit a tendency to sweat or exude oil from the binder and also cause.loss of frangibility.

The preferred oily mixtures generally contain approximately'an equalamount by weight of one or more compatible oils and one or moreincompatible oils.

The total amount of oily material present in the transfer layers of thepresent invention always exceeds the amount by weight of the resinous orfilm-forming binder material. The upper limit is determined only by thedegree of softness desired, amounts-up to about ten times the weight ofthe binder material being suitable in some. cases.

The transfer sheets of the present invention are prepared by coating asuitable flexible foundation such as paper, cellulose acetate or Mylar,etc. with a coatingof a synthetic thermoplastic resinous or film-formingbinder material which is preferably at least partially soluble in theconventional spirit duplicating fluids, a miscible mixture of at leastonenon-volatile oily material which is.

the art. The preferred method, howeven'is the solvent application inwhich one or more volatile organic solvents are used which dissolve thebinder material and are at least substantial non-solvents for thehectograph dyestutf. After application of the coating to the foundation,the solvent is evaporated and there results .theformation of a frangibleand stable hectograph layer ,which'does not melt at elevatedtemperatures but becomes softbut not liquid or flowable at temperaturesequal to or exceeding 450 .1 which is the maximum temperature generallyused in thermographic or heat-transfer processes.

While the advantages of the present invention are important from thestandpoint of straight spirit .or gelatin hectograph duplication, thereisalso the other consideration involving the use of heat in preparingmasters.

There are at present two principal methods for accomplishing this whichare applicable to forming hecto masters. One is xerography and theother,.thermographic means involving infrared radiation.

in the first case, a xerographic image comprising conventionalresinouselectroscopic powders may be formed electrostaticaliy on a Xeroxplate andtransferred to the transfer layerof the solvent type ofhectograph sheet or to the working surface of a master sheet. The imagedsheet, together with a master or a solvent type of hectograph sheetunder sufficient pressure to hold the two firmly together, are subjectedto heat or infrared radiation in which action the xerographic resinpowder comprising the xerographic image is tackified and fused in theimaged so that-the master and hectograph layer are welded together atsaid imaged areas. On separation after cooling, the frangible dye layeris picked off in said imaged areas and adhered to the master sheet.

In the second case, the solvent type hectograp'h sheet is placedtogether with a master sheetand infrared radiatron-absorbing originalimages which are generally carried by a separate original sheet as shownby FIG. 2 of the drawing, but may also be present onthe surface of themaster sheet. The i superposed 'sheets are fed through a thermographicmachine having infrared radiation, in which act heat is developed in theoriginal infrared radiation-absorbing images, thereby causing a heatingand softening of the'hectograph layer and a welding thereof to themaster in said areas. On cooling and separation, hectograph images areformed on the master sheet corresponding either directly or in reverseto the original images.

To further improve upon the. weldingt'of the master to the hectographlayer, itrnay be advisable :to either film over the hectograph layer orapply a film' tothe master, said film havingparticular afiinity for themaster on the one hand or the hectograph layer on the other, as the casemay be, when hot, thereby efliectinga better, more complete transferafter cooling and separation. The whole point is thatthese solvent resinbonded type coatings, while they might soften. with heat, do. notliquet'y or flow out as does a wax coated sheet. Naturally it should beunderstood that a coating that becomes liquid under these temperaturesis inoperable in the case of xerography to form a master as describedbecause the whole hectograph'mass would block off and adhere to the saidmaster. Similarly, in the case of the thermographic method, thecriticality would .be much. greater when flowable ink is used because ofambient temperature developed in the machineand the tendency of thefoundation and master sheets to absorb some radiatiomwhereas with ahectograph coating that does not become molten or fluid but merelysoftens, the criticality of the temperature factor is greatly reduced.Naturally, various -modifications can be made in the composition of theresin bonded layer and/or undercoatings or supercoatings to fit anintended use, all of which will be well known in the art. The fact isthat besides having a better copying hectographic composition for.regular work, an addedadvantage can be found in the application of theelement to thermographic or xerographic duplicating methods.

As the non-volatile, non-compatible oily component, it has been. foundthat any normally liquid or semi-solid oleaginous material may be usedso long as it is not essentially compatible with the binder employed atroom temperature. Such materials vary of course with the binder butinclude, in the case of ethyl cellulose binder, oleaginouscompositions'such as most of the animal and mineral oils, petrolatum,lanolin and the like.

Illustrative of the non-volatile compatible oleaginous materials usefulin conjunction with ethyl cellulose binder material are the vegetableoils such as castor oil, linseed .oil and soybean oil, esters such asdioctyl phthalate and tricresyl phosphate, and the like.

The preferred oily material mixture is one which has a high viscosityand contains one or more oleaginous materials having thischaracteristic. For instance, mixtures containing high viscosity oilssuch as heavy bodied mineral oil and the like, or pasty semi-solid oilymaterials such as fats, lanolin, petrolatum and the like, provideexcellent results. The high viscosity of the mixture tends to render iteven less migratory than more fluid mixtures and thus improves upon theaging characteristics of the hectograph transfer sheets containing thesame.

It should be emphasized that the compatibility and incompatibility ofthe various oily materials differ depending upon the particular bindermaterial used and that the selection of an oil phase containing theaforesaid ratio of compatible and incompatible oils is within the skillof the art in view of the present teachings.

The following table is set forth as an illustration of several miscible'oil mixtures which may be used according to the present inventiontogether with an ethyl cellulose binder material. The numbers listeddesignate the relative parts by Weight of each oil.

Oils Miseible, it any 8 Refined Rapeseed-.. Refined'Rapeseed.--

2 Castor 5 Castor.

2 Castor. 4 Mineral 4 Refined Rapeseed. 6 Castor- 2 Mineral 2 RefinedRapeseed. 3 Castor. 3 Light Mineral 4. Butyl Stearate.

'4 Castor 2Heavy Mineral 4 Refined Rapeseed. 2 Castor-.- 4 Miner 4 LardOil.

6 Castor. 2 Mineral. 2 Lard Oil.

2 Castor 4 Mineral. 4 Butyl Stearate.

6 Castor 2 Mineral- 2 Butyl Stearate.

5 Gaston.-. 5 Lard Oil.

5 Castor 5 Butyl Stearate 3 Tricresyl Phosphate.-- 4 Mineral. 3 RefinedRapeseed. 3 'lricresyl Phosphate.-- 4 Mineral- 3 Butyl Stearate.

3 Dloctyl Phthalate.. 7 Mineral.

It should be understood that the foregoing miscible oil mixtures may beused with other binder materials provided that the compatibility andincompatibility requirements are met. For instance, many vinyl resinssuch as polyvinyl actate are compatible with oils such as tricresylphosphate and dioctyl phthalate and incompatible with oil such asmineral oil, rapeseed oil and the like.

The following examples are illustrative only and should not beconsidered as limitative.

Example 1 The mixture was then spread evenly on a suitable flexiblefoundation 10, such as paper, by suitable coating apparatus and allowedto cool and to set by evaporation of the solvent to form a smooth,pressure-transferable and heattransferable hectograph coating 11 havingthe properties described.

The prepared transfer sheet is compared with a conventional hot melt waxhectograph sheet in the following manner: Two Original sheets 30 whichare desired to be copied are placed face-up; then the novel hectographsheet of the present invention is placed face-up over the first originaland the conventional hectograph sheet is placed face-up over the secondoriginal; next a suitable master sheet 20 is placed over each of thetransfer sheets, in contact with the hectograph layer, to form a pack.Each pack is then passed through a Ther-mo-Fax machine. The infraredradiation of the machine is focussed on the master sheet and penetratesthrough to the original sheet where it is absorbed by the images 31 onthe original sheet and converted to heat in these areas. The heatgenerated by the images causes the overlying transfer sheet to heat upover the imaged areas thereby bonding the master to said imaged areas.

Upon emergence from the machine, the pack carrying the conventionalhectograph sheet is found quite inferior for many reasons. It appearsthat the imaging layer of the conventional hectograph sheet melts andbecomes fluid at the existing temperatures and spreads onto the I mastersheet due to the overall ambient temperature of the thermographicmachine, the radiation absorbing tendency of the foundation and mastersheets, and the lack of heat resistance of the transfer layer.

None of these defects are present in the pack containing the novelhectograph sheet of the present invention. The imaging layer of thissheet does not become fluid at the temperatures of the thermographicmachine but merely becomes softened and adhesive or tacky over the imageareas of the original sheet. The hectograph layer over these areas fusesitself to the master sheet and transfers thereto as images 11a in asubstantially stenciling manner to give a sharp, clear master sheethaving minimal background stains. Likewise the present transfer sheetspermit for varying the density of the copies produced due to their heatresistance over a relatively wide temperature range. For instance, Wheredenser copies and a longer running master sheet are desired, the speedat which the pack is run through the thermographic machine may bedecreased, thus allowing for increased heat formation in the imagedareas and a denser imaged master sheet.

Each of the prepared master sheets are tested in-a spirit duplicatingmachineand the novel sheets of the present invention result in cleaner,sharper and over 50% more numerous copies than the master sheet preparedfrom the conventional hectograph sheet.

Example 2 Parts by weight Castor oil (compatible) 4.8 Mineral oil(incompatible) 8J0 Butyl stearate (compatible) 8.0 Hecto graph dyematerial (Du Pont Spirit Black #3) 19.2 Ethyl cellulose 5:0 Solvent(toluol or the like) 55.0

The above ingredients are mixed to a coatable consistency and coated ona suitable foundation as in Example 1 to form a hectograph transfersheet. I

This transfer sheet is then placed in face-to-face contact with aselenium plate carrying electrostatic images comprising electroscopicresinous thermoplastic powder under sufiicient pressure to keep the twoelements in close contact. A corona discharge is applied, therebyreversing the polarity, and upon removal of the hectograph sheet thepowdered images 12 are adhered to the hectoarvmee graph layer 11. Thehectograph sheet bearing the powdered images is then placed inface-to-face contact with a master sheet 20 to form a pack which isheated to a temperature of, between 40045,0 F. The powdered imagestackify and fuse to the master sheet and the hectograph layer in theareas overlying the powdered images.

' it is preferred that the master and transfer sheets be of Thus, uponseparation of the sheets there is formed a master sheet 21), carrying asubstantial amount of hectograph material 11a in the electrostaticimageareas 12, which maybe, used to prepare many sharp copies in thespirit process.

An alternative xerographic method is to transfer the Xerox images fromthe plate to master sheet and then i superpose the master withthe'hectograph transfer sheet and place them in the Xerox oven.

An attempt to employ conventional hot melt wax hectograph transfersheets in either of these processes fails due to the fact that the. dyelayer melts to a fluid state at the required temperatures and the fluidtransfers to the master sheet throughout.

It has been found that amounts of binder as low as 2% was high as 25%based upon the total dry weight of the transfer compositionmay be used,and that the amount of hectograph dye may be as high as 10 times theweight of binder used. It is preferred that the dyestuif be present inan amount ranging from about 35 to about 65% of the dry weight of thetransfer coinpo- 1 sltion.

As the resinous or film-forming binder material in the presenthectograph compositions, it is preferredto employ those which are atleast partly soluble in the conventional spirit duplicating fluids whichcomprise alcohol, such as ethyl alcohol, and water. In this regard, the

preferred film-forming materials include cellulosic resins such as ethylcellulose; vinyl resins such as polyvinyl acetate; alcohol-soluble nylonpolyamides; chlorinated polyphenyl resins such as the Arochlors;'unesterified rosin- Gther maleic resins such as the Amberols and thelike. siutable binders include vinyl: chloride-vinyl acetate copolymerssuch as Vinylite VYHH, cellulose acetate,

'methylcellulose, carboxymethyl cellulose,.st'yrene homopolymers andcopolymers such as 'lsopol P-ll4-RM (styrene-isoprene), and'others. Itis useful in some instances to overcoat the hectograph layer with a waxsupercoating cont'ainingfrangible, tacky material such as beeswax,Indopol and Vistanex to improve the. attraction of the'transfer layerfor the master sheet.

In the formulations set forth hereinbefore it should be emphasized thatthe named substantially compatible?" oils are not usually completelycompatible with the binder materials, nor are the substantiallyincompatible'oils completely so. In determining the relativecompatibilities the binder material and oil are mixed in the cold,

such a nature as to. allow the radiation to easily pass through. In thisregard, transparent, translucent and transpicuous sheetsareverysatisfactory,.such as clear plastic, frosted or crazed plastic,glassine paper, etc. Likewise the hectograph dye layer should bepermeable to infrared radiation and should notcontain any materials.which absorb infared radiation to any substantial degree. Suitableinfrared-permeable dyes include rhodaminedyes; malachite green;safranine dyes and the like.

As defined by the appendantclaims, the particular dyestufi used is onewhich is insoluble to the volatilesolvent used to apply the transferlayer and insoluble in the miscible mixture of oleaginous modifyingagents present in the transfer layer. Preferred volatile coatingsolvents include thehalogenated hydrocarbons such as carbontetrachloride, dichloroethane and the like, .as wellas hydrocarbonsolvents such'as toluol, xylene and the like.

Variations and modificationszmay be made within the scope of the claimsand portions of the improvements may be used without others.

We claim: 7

1. A pressure-sensitive hectograph transfer element comprising afiexiblefouridation carrying a volatile-solvent-applied frangibletransfer layer which is substantially completely transferable to, amaster sheet in areas impressed with imaging pressure, saidtransferlayer comprising f-rom.3%. to 25% by Weight of a synthetic thermoplasticfilm forming bindermaterial, an amount of a miscible mixture of at leasttwo oleaginous modifying agents in excess of the amount of said bindermaterial, said miscible mixture including from 20% to 80% by weight ofat least one oleaginous'material which is substantially compatible with'said binder' material and from 80% to 20% by weight'of at least oneoleaginous material which is substantially non-compatible with saidbinder material, and from 35% to by weight of a spirit-solublehectograph dyestuff, said dyestuff being substantially insoluble in saidoleaginous materials and insoluble in the volatile solvent used to applysaid transfer layer.

2. A pressure-sensitive hectograph transfer element according to claimlin which the binder material is a cellulose plastic. s

3. A pressure-sensitive hectograph transfer element according to claim 1in which the oleaginous materials are liquid oils. 7

References Cited by the Examiner 1 UNITED STATES PATENTS r Marron1'17--36.1

' 2,820,717 1/58 Newman et al. 1 1736.1

' 2,861,515 11/58 Dalton etal. 101-1494 2,893,890 7/59 Harvey j1'1736.12,944,037 7/60 Clark 117-3611 3,029,157 4/62 Sutheim et al. 11736.13,037,879 6/62 Newman et al. 117-361 3,054,692: 9/6-2 Newman et al. f117-175 RICHARD DQNEVIUS, Primary Examiner. MURRAY KATZ, DAVID ,KLEIN,'-Examiners,

1. A PRESSURE-SENSITIVE HECTOGRAPH TRASFER ELEMENT COMPRISING ASFLEXIBLE FOUNDATION CARRYING A VOLATILE-SOLVENT-APPLIED FRANGIBLETRANSFER LAYER WHICH IS SUBSTANTIALLY COMPLETELY TRANSFERABLE TO AMASTER SHEET IN AREAS IMPRESSED WITH IMAGING PRESSURE, SAID TRANSFERLAYER COMPRISING FROM 3% TO 25% BY WEIGHT OF A SYNTHETIC THERMOPLASTICFILM-FORMING BINDER MATERIAL, AN AMOUNT OF A MISCIBLE MIXTURE OF ATLEAST TWO OLEAGINOUS MODIFYING AGENTS IN EXCESS OF THE AMOUNT OF SAIDBINDER MATERIAL, SAID MISICIBLE MIXTURE INCLUDING FROM 20% TO 80% BYWEIGHT OF AT LEAST ONE OLEAGINOUS MATERIAL WHICH IS SUBSTANTIALLYCOMPATIBLE WITH SAID BINDER MATERIAL AND FROM 80% TO 20% BY WEIGHT OF ATLEAST ONE OLEAGINOUS MATERIAL WHICH IS SUBSTANTIALLY NON-COMPATIBLE WITHSAID BINDER MATERIAL, AND FROM 35% TO 65% BY WEIGHT OF A SPIRIT-SOLUBLEHECTOGRAPH DYESTUFF, SAID DYESUFF BEING SUBSTANTIALLY INSOLUBLE IN SAIDOLEAGINOUS MATERIALS AND INSOLUBLE IN THE VOLATILE SOLVENT USED TO APPLYSAID TRANSFER LAYER.